This invention relates to a terminal strip for making terminals and more particularly to terminals having a compliant portion and to a method for making such.
A terminal is known to electrically interconnect one electrical component to another through a pressure fitted electrical connection at either or both ends. The terminal is typically made of a cost effective tin plated copper alloy providing a reliable electrical connection. When making or breaking the electrical connection, the tin oxide layer of the terminal essentially cracks permitting clean tin to ooze out through the crack. The clean tin bonds to the connector of the electrical component providing a very stable electrical connection
Fretting corrosion is a known phenomenon which can cause otherwise stable tin plated copper alloy electrical connections to fail. For fretting corrosion to occur, there must be a small degree of movement or rubbing between the pressure fitted tin plated terminal interface. Such movement is usually the result of vibration from one or both of the electrical components. Fretting or the rubbing of the terminal interface together typically occurs only when the vibration or displacement between components is of a small magnitude measured in microns (i.e. 10-100 microns) and the pressure between the interface is low. Fretting corrosion occurs when the once clean tin is exposed to the air as a result of movement, wherein the tin quickly forms into an electrically insulating tin oxide film. With repeated motions, the debris of tin oxide builds up until the electrical connection fails.
Fretting corrosion can be eliminated by preventing the electrical components from vibrating, or utilizing gold or silver based terminal contact coatings which resist fretting corrosion. Unfortunately, either means may not be practical or may be cost prohibited depending upon the application.
The present invention provides an elongated terminal strip having a series of terminals and Cut lines disposed therebetween. Each terminal has a compliant portion extending longitudinally with respect to the elongated terminal strip from one laterally extended cut line to the next succeeding cut line. An electrical contact first portion extends laterally outward from the compliant portion between the two adjacent cut lines. An opposing second portion, extends laterally outward from the opposite side of the compliant portion. The first and second portions electrically engage respective electrical components. If either electrical component should vibrate, the compliant portion of the terminal will extend, retract or twist, in other words, will move within a three dimensional array, thereby enabling either the first or second portions of the terminal to move relative to the respective vibrating electrical component preventing any relative movement at the electrical contact points and eliminating fretting concerns.
The compliant portion has at least one slot which extends longitudinally with respect to the elongated terminal strip from either one of the adjacent cut lines to an end of the slot disposed within the compliant portion of the terminal. Preferably, the compliant portions have a plurality of slots which extend from both of the adjacent cut lines. For instance, preferably the compliant portion has a leading slot extended rearward within the compliant portion. The leading slot is disposed between two trailing slot which extend forward within the compliant portion from a succeeding cut line to the cut line communicating with the leading slot. The trailing slots have ends disposed within the compliant portion lying slightly rearward of the cut line communicating with the leading slot. The ends of the trailing slots are disposed laterally outward with respect to the leading slot.
A feature of the present invention is the reduction of fretting corrosion caused by vibrating electrical components.
Another feature of the invention is the production of a cost effective and robust compliant portion of the terminal.